Commit 9ca71874 authored by Francis Laniel's avatar Francis Laniel Committed by Jakub Kicinski
Browse files

Modify return value of nla_strlcpy to match that of strscpy. 



nla_strlcpy now returns -E2BIG if src was truncated when written to dst.
It also returns this error value if dstsize is 0 or higher than INT_MAX.

For example, if src is "foo\0" and dst is 3 bytes long, the result will be:
1. "foG" after memcpy (G means garbage).
2. "fo\0" after memset.
3. -E2BIG is returned because src was not completely written into dst.

The callers of nla_strlcpy were modified to take into account this modification.

Signed-off-by: default avatarFrancis Laniel <laniel_francis@privacyrequired.com>
Reviewed-by: default avatarKees Cook <keescook@chromium.org>
Signed-off-by: default avatarJakub Kicinski <kuba@kernel.org>
parent 8eeb99bc

include/net/netlink.h

+1 −1
Original line number Diff line number Diff line
@@ -506,7 +506,7 @@ int __nla_parse(struct nlattr **tb, int maxtype, const struct nlattr *head, 
		struct netlink_ext_ack *extack);

int nla_policy_len(const struct nla_policy *, int);

struct nlattr *nla_find(const struct nlattr *head, int len, int attrtype);

size_t nla_strlcpy(char *dst, const struct nlattr *nla, size_t dstsize);

ssize_t nla_strlcpy(char *dst, const struct nlattr *nla, size_t dstsize);

char *nla_strdup(const struct nlattr *nla, gfp_t flags);

int nla_memcpy(void *dest, const struct nlattr *src, int count);

int nla_memcmp(const struct nlattr *nla, const void *data, size_t size);

include/net/pkt_cls.h

+1 −1
Original line number Diff line number Diff line
@@ -512,7 +512,7 @@ tcf_change_indev(struct net *net, struct nlattr *indev_tlv, 
	char indev[IFNAMSIZ];

	struct net_device *dev;



	if (nla_strlcpy(indev, indev_tlv, IFNAMSIZ) >= IFNAMSIZ) {

	if (nla_strlcpy(indev, indev_tlv, IFNAMSIZ) < 0) {

		NL_SET_ERR_MSG_ATTR(extack, indev_tlv,

				    "Interface name too long");

		return -EINVAL;

lib/nlattr.c

+25 −14
Original line number Diff line number Diff line
@@ -710,33 +710,44 @@ EXPORT_SYMBOL(nla_find); 


/**

 * nla_strlcpy - Copy string attribute payload into a sized buffer

 * @dst: where to copy the string to

 * @nla: attribute to copy the string from

 * @dstsize: size of destination buffer

 * @dst: Where to copy the string to.

 * @nla: Attribute to copy the string from.

 * @dstsize: Size of destination buffer.

 *

 * Copies at most dstsize - 1 bytes into the destination buffer.

 * The result is always a valid NUL-terminated string. Unlike

 * strlcpy the destination buffer is always padded out.

 * Unlike strlcpy the destination buffer is always padded out.

 *

 * Returns the length of the source buffer.

 * Return:

 * * srclen - Returns @nla length (not including the trailing %NUL).

 * * -E2BIG - If @dstsize is 0 or greater than U16_MAX or @nla length greater

 *            than @dstsize.

 */

size_t nla_strlcpy(char *dst, const struct nlattr *nla, size_t dstsize)

ssize_t nla_strlcpy(char *dst, const struct nlattr *nla, size_t dstsize)

{

	size_t srclen = nla_len(nla);

	char *src = nla_data(nla);

	ssize_t ret;

	size_t len;



	if (dstsize == 0 || WARN_ON_ONCE(dstsize > U16_MAX))

		return -E2BIG;



	if (srclen > 0 && src[srclen - 1] == '\0')

		srclen--;



	if (dstsize > 0) {

		size_t len = (srclen >= dstsize) ? dstsize - 1 : srclen;

	if (srclen >= dstsize) {

		len = dstsize - 1;

		ret = -E2BIG;

	} else {

		len = srclen;

		ret = len;

	}



	memcpy(dst, src, len);

	/* Zero pad end of dst. */

	memset(dst + len, 0, dstsize - len);

	}



	return srclen;

	return ret;

}

EXPORT_SYMBOL(nla_strlcpy);

net/sched/act_api.c

+1 −1
Original line number Diff line number Diff line
@@ -939,7 +939,7 @@ struct tc_action *tcf_action_init_1(struct net *net, struct tcf_proto *tp, 
			NL_SET_ERR_MSG(extack, "TC action kind must be specified");

			goto err_out;

		}

		if (nla_strlcpy(act_name, kind, IFNAMSIZ) >= IFNAMSIZ) {

		if (nla_strlcpy(act_name, kind, IFNAMSIZ) < 0) {

			NL_SET_ERR_MSG(extack, "TC action name too long");

			goto err_out;

		}

net/sched/cls_api.c

+1 −1
Original line number Diff line number Diff line
@@ -223,7 +223,7 @@ static inline u32 tcf_auto_prio(struct tcf_proto *tp) 
static bool tcf_proto_check_kind(struct nlattr *kind, char *name)

{

	if (kind)

		return nla_strlcpy(name, kind, IFNAMSIZ) >= IFNAMSIZ;

		return nla_strlcpy(name, kind, IFNAMSIZ) < 0;

	memset(name, 0, IFNAMSIZ);

	return false;

}

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